This invention relates to methods for evaluating designs of products, and more particularly, to methods for evaluating nuclear power plants and components therein.
Nuclear power plants include a containment structure that houses the nuclear reactor portion of the plants. Throughout the development of the nuclear power industry, a large number of key experiments have been performed which characterize various aspects of nuclear power plant containment structure performance under postulated accident conditions. These experiments include such large scale tests as: the Marviken suppression pool dynamics test program; the Carolinas-Virginia Tubular Reactor (CVTR) containment experiments; extensive HDR full scale containment experiments; the Containment Systems Test Facility (CSTF) experiments; the Battelle-Frankfurt containment compartmentalization tests; and the NUPEC containment experiment that has been characterized as an International Standard Problem (ISP-35).
These numerous experiments provide key data and insights related to the containment structure performance under a variety of postulated accident conditions. These data and insights specifically relate to those features of the containment structure that would influence radioactive releases to the environment assuming a Design Basis Accident (DBA) leakage rate. Furthermore, these data, combined with more numerous separate effects experimental data, characterize individual aspects of the different containment designs that have been used throughout the United States, Europe and the Far East. Separate effects tests are those limited scale experiments that are generally well instrumented but focus on a specific physical process (phenomenon) such as condensation. Large scale tests approach the size of a containment building and include all the relevant physical processes, i.e. condensation, natural circulation, compartmentalization, containment sprays, etc.
To date, individual experiments have been compared to a variety of approaches for designing and evaluating containments with respect to their licensing basis, which includes the releases of radioactive fission products due to the design basis leakage rate. However, no uniform process has been established to synthesize the huge amount of experimental data available from these large scale containment experiments and additional small scale separate effects experiments in a technically defensible manner such that the ensemble of the data can be used to evaluate the performance of given containment designs. Furthermore, no methodology has ever synthesized this database across a spectrum of containment designs such that the technical bases for decision making is uniform for all designs. The various types of nuclear power plant containments include those used for Boiling Water Reactors (BWRs), specifically the Mark I, Mark II and Mark III containment designs, as well as for the Pressurized Water Reactor (PWRS) which include large dry, subatmospheric and ice condenser containment designs.
It would be desirable to have a uniform method for the evaluation of a product design that uses the data resulting from various independent tests and simulations of various aspects of the product. More particularly, it would be desirable to have a uniform method for the evaluation of nuclear reactor containment structures that uses data resulting from various large scale experiments and separate small scale separate effects experiments relating to such containment structures.
This invention provides a structured method of evaluating a design and includes the steps of assembling a first database of test results; selecting physical models relevant for the design to be evaluated; comparing a first set of test results of these models to test results in the first database of test results; establishing uncertainty boundaries for the first set of test results of the models; assembling a second database of test results; determining whether the test results of the second database of test results are within the uncertainty boundaries of the model; and evaluating an actual or proposed design based upon the resulting models when test results of the second database of test results are within the uncertainty boundary.
If the second data base test results are not within the uncertainty boundaries of the model, the process of assembling the first database and selecting the relevant physical models is repeated and adjusted so that the test results of the second database will fall within the uncertainty boundaries of the resulting integral model. This forces closure of the process. The physical models are mathematical models (algorithms) that are used to model the design, or components thereof, that is under evaluation.